. Precious stones, a popular account of their characters, occurrence and applications, with an introduction to their determination, for mineralogists, lapidaries, jewellers, etc. With an appendix on pearls and coral. Precious stones; Pearls; Corals. SPECIFIC GRAVITY 19 (3) Finally the stone is fixed in the clip p and immersed in the water; the weight now required to restore equilibrium was 3-97857V^, The loss of weight of the stone was* therefore (3-9785 - 3-«12)iV = 0-1665iV, and the specific gravity 0*443 d = ,f^nf- = 2"66. This is again the specific gravity of rock- crystal (quartz
. Precious stones, a popular account of their characters, occurrence and applications, with an introduction to their determination, for mineralogists, lapidaries, jewellers, etc. With an appendix on pearls and coral. Precious stones; Pearls; Corals. SPECIFIC GRAVITY 19 (3) Finally the stone is fixed in the clip p and immersed in the water; the weight now required to restore equilibrium was 3-97857V^, The loss of weight of the stone was* therefore (3-9785 - 3-«12)iV = 0-1665iV, and the specific gravity 0*443 d = ,f^nf- = 2"66. This is again the specific gravity of rock- crystal (quartz), and the stone may therefore be identified as quartz. This method of determination enables the specific gravity of a stone to be found correctly to two places of decimals with very little trouble, provided that the precautions already mentioned have been observed : namely, that the stone is free from air-bubbles, that it does not come in contact with the sides of the vessel nor rise out of the water, and that it is not too small. The specific gravity of a stone weighing half a carat, that is about one-tenth of a gram, can be determined accurately to the second place of decimals ; though the figure in the second place will be uncertain when the stone only weighs ;| or I- of a carat, the determination is still useful for practical purposes. With stones smaller than this, however, the results are not sufficiently reliable. If supported in the basket shown in Fig. 2, or in a net made of platinum gauze fixed to the clip, a number of such small stones may be weighed together. In this method, as previously, the first weighing, giving the constant for the counterpoise of the instrument and the particular wire and clip to be used, may be performed once for all, so that afterwards only two weighings are necessary, and this effects a considerable saving in time. Should the stone, whose specific gravity is to be determined, be so heavy that it raises the counter- poise by its own weight
Size: 847px × 2951px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectpreciousstones, booky
